Greek beach + giant moon

These were taken with fuji sensia 100 and were done by taking a shot of the moon with a 300mm telephoto and then a double exposure with the landscape shot with a 24mm lens.
The idea was to simply create an intense photo by coupling a large moon with a typical landscape shot.
Problem is I didn't expose the moon correctly... I know I should use spot metering, how should I accurate expose the moon?
I figured one way would be to spot meter the moon, then meter away from it and take the average?

Another thing, I did not do any post-editing and would like some suggestions as to what to touch-up. I'm very new to photoshop though.

from my experience, you need to seriously underexpose the moon.
It is the second brightest object in the sky. In my experience it is really hard to meter the moon. The best way would be to spot meter and just go with that. When i have shot with 100 ISO fugi film before, i have gotten good moon shots at 200mm 1/250th f/8. Either way, every time i have shoot the moon, my good photos ended up being shot at a much faster shutter speed and f stop then i expeced. The moon is quite bright